Patent Document 1 discloses an antenna provided to a radar apparatus. This antenna is rotatably configured so that an elevation-depression angle and an azimuth angle change.
Patent Documents 2 and 3 disclose control devices, each controls attitude of a directional antenna mounted on a movable body. The antenna has two rotation axes located within a horizontal plane, and one rotation axis parallel to a vertical direction. The control devices control the directional antenna to face toward a particular satellite by rotating the directional antenna around the rotation axes described above even when the movable body rocks or a traveling direction thereof changes. Although the directional antennas of Patent Documents 2 and 3 have three rotation axes, the directional antennas cannot rotate in their circumferential directions.
Patent Document 4 discloses a control device which adjusts an orientation of a directional antenna so that it faces toward a particular satellite, similar to Patent Documents 2 and 3. In the control device of Patent Document 4, the directional antenna can be rotated so that an elevation-depression angle, an azimuth angle and an antenna circumferential angle (a rotational angle of the directional antenna in its circumferential direction) change.